After every major terrorist attack by Islamist terrorists in a Western country, there follows a familiar debate about who is really to blame. One side trots out the weary old trope that the terrorists simply "hate our values", and other side claims it's the fault of Western governments for sending their troops into Muslim countries.

There's a national election campaign underway in Britain, so the ghastly Manchester bombing last week has revived this argument. It started when Labour leader Jeremy Corbyn (who voted against the invasion of Afghanistan in 2001, the invasion of Iraq in 2003, and the seven-month bombing campaign that overthrew Libya's dictator Muammar Gaddafi in 2011) made a speech in London on Friday.

"Many experts, including professionals in our intelligence and security services, have pointed to the connections between wars our government has supported or fought in other countries and terrorism here at home," he said.

Prime Minister Teresa May responded: "Jeremy Corbyn has said that terror attacks in Britain are our own fault . . . and I want to make something clear to Jeremy Corbyn and to you: there can never be an excuse for terrorism, there can be no excuse for what happened in Manchester."

But both sides in this argument are wrong. The Salafi extremists who are called Islamists in the West (all of them Sunnis, and most of them Arabs) do hate Western values, but that's not why they make terrorist attacks on the West. And it's not because of Western foreign policies either. There were no major Western attacks on the Arab world in the years before the 9/11 atrocity in 2001.

There had been plenty of attacks in the past: the Western conquest of almost all the Arab countries between 1830 and 1918, Western military support for carving a Zionist state out of the Arab world as the European imperial powers were pulling out after 1945, Western military backing for Arab dictators and absolute monarchs ever since.

With the support of most Arab countries, the West drove Saddam Hussein out of Kuwait in the first Gulf War in 1990-91. And between then and 9/11 the West did nothing much to enrage the Arab world.

But there was violence in many Arab countries as Islamist revolutionaries, using terrorist tactics, tried to overthrow local kings and dictators. Up to 200,000 Arabs were killed in these bloody struggles between 1979 and 2000, but not one of the repressive regimes was overthrown. By the turn of the century it was clear terrorism against Arab regimes was not working. The Islamists needed a new strategy.

The man who supplied it was Osama bin Laden. He fouth the Soviet invasion of Afghanistan in 1979, a war Islamists actually won. Having lost 14,000 dead, the Russians gave up and went home in 1989 and the Afghan Islamists (the Taliban) came to power as a result.

Bin Laden realised that this could be a route to power for the Islamists of the Arab world as well: provoke the West to invade Muslim countries, lead the struggle against the Western occupation forces - and when the Western armies finally give up and go home (as they always do in the end) the Islamists will come to power.

That was why he founded al-Qaida, and 9/11 was intended to sucker the United States into playing the role of infidel invader. Western governments have never recognised this obvious fact because they are too arrogant ever to see themselves as dupes in somebody else's strategy. Their foreign policy error was to fall for bin Laden's provocation hook, line and sinker and they are still falling for it sixteen years later.